Motion simulators are used for a variety of purposes, including entertainment and flight simulation for example, and usually comprise an upper platform which is mounted for movement relative to a fixed lower base and is operatively connected thereto by a plurality of actuators which move the platform as required in a desired number of degrees of freedom. Generally, undesirable vibrations are required to be limited as much as possible in order to minimize audible noise and wear of the simulator parts. In flight simulators, unwanted vibrations felt by the pilot can result in un-realistic representations of the performance and feel of the true airplane or helicopter. However, such a flight simulator must nonetheless reproduce certain vibrations which are true to those experienced in the actual aircraft, such as certain low frequency vibrations for example.
In most known motion simulation system hydraulic actuators are used, as opposed to other types of linear actuators, as these actuators are well proven and produce minimal undesirable vibrations. However, hydraulic actuators present several disadvantages, among which are a high maintenance requirement, the need for costly and noisy accessory equipment such as pumps, hosing and the like, the risk of contamination or leakage of the hydraulic fluid, and a low energy efficiency.
Electromechanical linear actuators require less maintenance than hydraulic actuators, and are generally less complex and costly to operate. However, electromechanical linear actuators have proved to date unable to cost-effectively reproduce the performance of their hydraulic counterparts, as many electromechanical linear actuators produce more undesirable vibrations, which are ultimately transferred to the motion platform and therefore the user therein, causing an elevated audible noise level in the motion cabin and a reduced life of the actuated equipment as a result of the additional vibrations. Flight simulators incorporating pneumatic or hydraulic damping systems are known, and typically attempt to reduce all transmitted vibrations by reducing the actuator load. Such damping systems are generally complex, costly and include a high number of parts which further augments the risk of equipment failure. Moreover, in most cases, control systems are necessary to prevent a failure of the damping system from damaging the motion simulator cabin or endangering a user of the motion simulator.
Other simpler vibration dampers for use with actuators are known, but are impractical for many applications including flight simulators because such dampers generally reduce all vibrations, including the desirable “cues” which the flight simulator must reproduce in order to adequately simulate an aircraft environment.